The present invention relates generally to the use and preparation of balloon catheters for angioplasty and other surgical procedures and more specifically, to a multiple pleated balloon and a device for forming multiple pleats in such balloons.
The use of angioplasty to relieve blockages, or occlusions, of blood vessels has increased significantly in recent years. Angioplasty typically involves the insertion of an inflatable balloon into an occluded blood vessel and positioning the balloon at the occlusion. The balloon is then rapidly inflated and deflated in order to expand the occlusion and restore the blood vessel to its original, workable size.
Angioplasty catheters which are used for these procedures typically include a guidewire, a balloon catheter having a guide lumen which receives the guidewire, an inflation lumen extending to the distal end of the catheter and an inflatable balloon positioned at the distal end of a catheter over an opening of the inflation lumen. The balloons used with such catheters typically have an inflatable body portion disposed between two leg portions. The leg portions have a diameter which may be slightly less than the diameter of the catheter at its distal end in order to provide a tight seal which permits inflation and deflation of the balloon. The balloon body portion may have a diameter greater than that of the leg portions and the catheter shaft. Typically, this diameter corresponds to the actual diameter of the balloon when inflated, particularly when a non-expandable material is used for construction of the balloon.
The inflated diameter of angioplasty balloons may range anywhere from between 1.5 to 5.0 mm, while the diameter the catheter at its distal end is in the order of 1.0 mm. The excess balloon material is rolled when deflated upon the catheter distal end portion to facilitate insertion of the balloon into the blood vessel. When so prepared, the balloon will not impinge upon the walls of the blood vessel as it is being positioned within the blood vessel at the site of the occlusion. This balloon preparation is usually accomplished by manually rolling the body of the balloon onto the catheter shaft. Because of the very small dimensions of these balloons, it is difficult and time consuming to ensure that the balloon is accurately and preferably uniformly folded upon itself.
When such balloons are rolled upon their supporting catheters with only one or two folds, the deployment of the balloon during inflation may not occur in a uniform manner, leading to problems in opening the occlusion in the vessel. Additionally, in clearing the occlusion the balloon typically undergoes rapid inflation and deflation. In balloons having one or two folds, when the balloon is deflated, the folds may be too large to permit the balloon to pass rearwardly through the occlusions.
U.S. patent application Ser. No. 589,766, assigned to the assignee of the present invention, describes the use of a multiple part balloon press for forming folds in an angioplasty balloon in which the balloon press has two balloon-contacting members with a central channel extending along at least one of the balloon contacting members. Although this device is effective for forming two opposing folds in the catheter balloon, The press must be used repeatedly at different angular orientations in order to form more than two folds in the catheter balloon. It may be difficult to utilize this device to form more than two uniform folds in the catheter balloon. Using the device in this manner may lead to undesirable inaccurate forming of folds which may affect the inflation properties of the balloon.
U.S. Pat. No. 5,342,307, issued Aug. 30, 1994 and U.S. Pat No. 5,350,361, issued Sep. 27, 1994 describe dilation balloons with three folds. Although the balloons therein have three folds, the diameter of the balloon in an uninflated state is still relatively large due to the three folds, and a physician may have some difficultly in pulling the distal end of the catheter rearwardly through a lesion in the blood vessel. Additionally, in balloons having three such folds, the folds define three "wings" of the balloon which must be wrapped around the catheter shaft to facilitate removal of the catheter and balloon from the blood vessel. The length of these wings are such that they require the catheter distal end to be rotated for almost one revolution to complete the wrapping of the balloon wings or folds upon the catheter. This increases the complexity of the dilation procedure. To applicants' belief, there are no dilation balloons in the art that utilize more than three folds.
The present invention therefore is directed to a six-pleated catheter angioplasty balloon and a device for forming multiple pleats in such balloons while they are attached to the catheter shaft and which simplifies rolling or folding of the balloon body onto the catheter shaft. The present invention therefore ensures that the proper folded configuration of the balloon on the catheter distal end portion is achieved prior to insertion of the balloon catheter into the blood vessel.